Miners' Day (Dzień Górnika) is a traditional professional holiday in Poland celebrated on December 4. It is also known as Barbórka because it coincides with the feast day of Saint Barbara, the patron saint of miners and other who work with explosives.

According to legend, Saint Barbara was the daughter of a rich pagan. She secretly converted to Christianity and was cruelly tortured, but held true to her faith. Finally she was beheaded by her father. As punishment for carrying out the death sentence, he was struck by lightning and died. As St. Barbara's legend is associated with lightning, she became the patron saint of miners, military engineers, artillerymen, and armorers.

In Poland, St. Barbara's Day has been informally celebrated as Miners' Day for decades. It is also regarded as the professional holiday of geologists and all specialists engaged in the fossil fuel industry. It is celebrated with special church services, marching band performances, concerts, balls, and other festive events and activities.

Additionally, St. Barbara's Day is celebrated by some mining institutions in other countries, such as Australia. It is also marked by artillery units and sub-units in the British, Australian, Canadian, New Zealand, Irish, United States, and Norwegian armed forces.